Learn MICRONAUT with Real Code Examples

Micronaut is designed for microservices and serverless computing, with fast startup and minimal memory overhead.

It uses compile-time dependency injection and AOP to avoid reflection and runtime proxies.

Supports reactive programming and non-blocking HTTP clients/servers.

Built-in support for cloud-native features like service discovery, configuration, and distributed tracing.

Works with Java, Kotlin, and Groovy on the JVM.

Annotation-based dependency injection

Reactive HTTP client and server

Integration with GraalVM for native images

Declarative configuration and environment profiles

Built-in service discovery and security features

Application - main Micronaut app context

Controller - handles HTTP requests

Service - business logic component

Bean - DI component managed by Micronaut

Reactive streams - for non-blocking data handling

src/main/java - application source code

src/main/resources - configuration files

src/test/java - unit and integration tests

build.gradle / pom.xml - build configuration

application.yml - app configuration

Generate project using Micronaut CLI

Define Controllers with `@Controller` and routes

Create Services annotated with `@Singleton` or `@Factory`

Inject beans using `@Inject` or constructor injection

Run and test app with Gradle/Maven commands

Beginner: simple REST endpoint

Intermediate: DI-based service layer

Advanced: reactive API with streaming responses

Expert: cloud-native microservice with service discovery

Auditor: analyze startup performance and memory usage

Micronaut vs Spring Boot: Micronaut has compile-time DI, Spring Boot is runtime reflection-based

Micronaut vs Quarkus: Both are low-memory, fast startup frameworks, Quarkus integrates more tightly with GraalVM

Micronaut vs Node.js: Micronaut is JVM-based, typed, and compiled; Node.js is interpreted and single-threaded

Micronaut vs Ktor: Micronaut is full-stack microservice-focused; Ktor is lightweight Kotlin web framework

Micronaut vs Vert.x: Micronaut emphasizes DI and microservices; Vert.x focuses on reactive event-driven applications

2018 – Micronaut initial release by OCI

2019 – Reactive HTTP client/server support

2020 – GraalVM native image support

2021 – Cloud-native features (Kubernetes, AWS Lambda)

2022–2025 – Continuous improvements and library integrations

Controller - handles HTTP requests

Service - business logic component

Bean - DI-managed object

Reactive Streams - for async data flow

GraalVM Native Image - ahead-of-time compiled executable